APPENDIX 



475 



c. Protocol 



" First Growth Tube. 

 * Second Growth Tube. 



At 2 min. intervals 0.1 ml. samples from tubes 4 and 5 are 

 plated by the agar layer technique. After incubation at 37 °C. 

 overnight the plaques are counted. 



d. Results. It is apparent from Table XXIII that the plaque 

 counts from the First Growth Tube (F.G.T.) are constant 

 through 21 min. but increase suddenly by 23 min. so the end 

 of the latent period comes between 21 and 23 min. The counts 

 from the Second Growth Tube (S.G.T.) increase steadily through 

 about 32 min. and remain constant from then on. Average 

 count during the latent period is 102 which, multiplied by the 

 dilution factor of 4 X 10^, indicates 4.1 X lO*^ infected bacteria/ 

 ml. of the adsorption tube. The multiplicity of infection is 

 0.08 and the per cent adsorption in 5 min. is 82. 



Average count after bacterial lysis is completed is 1 1 1 which 

 multiplied by the dilution factor of 10- in going from F.G.T. to 

 S.G.T. , gives a count of 11,100 in terms of the F.G.T. Average 

 burst size is then 11,100/102 = 109. Total time interval from 

 the end of the latent period to the completion of bacterial lysis 

 is called the rise period, in this case about 10 min. 



[Results of a similar experiment are expressed graphically in 

 the control curve of Fig. 4 (p. 172). Phage assays] are plotted 



